95 gst backfiring under high boost?

[matt1280]

I need help asap! my gst is backfiring back under high boost (anything over 4k rpms really). only mods i have are: intake, 3 inch exhaust turbo back and no cat. please help me this is my daily driver. under normal driving ( no boost) the car runs fine. i adjusted the idle by turning a screw on the throttle body because the car was cutting off when i stopped. i just changed the plugs and got a gas treatment. when i boost i can hear it spooling up but it is alot louder than before and it starts backfiring bad. maybe a loose line somewhere? any info would be helpful.

thanks

 

[andymoraitis]

Matt

Your symptoms and are mostly likely related to fuel or spark issues. Check or replace the following items if you haven't done so recently or if you aren't sure when they were last done:

1. Fuel filter
2. Plug wires
3. Spark plug gap (should be .028)
4. Boost leak test

If you have an aftermarket boost gauge, how many psi is the turbo running when the stuttering starts? Also, what kind of plugs did you install?

Get us some more info please,

Andy

 

[95talon_in_ma]

Just curious, How much did you turn that screw?

If it was cutting out when you pushed the clutch in, then it's probably related to this issue:
http://www.dsm.org/how-tos/tttt/tttt3.html

If you turned up the screw too much, you might have just caused a real rich condition (at idle) and potentiall clogged up those new plugs...

Also, "backfires" usually refers to when you have an exhaust leak at the header and it draws air back into upon deceleration.
If it "backfires" when you are accelerating, usually it's timing related. (my experience)

But you might just be referring to "Misfire" which is what would happen if your plugs were fouled. (Sounds something like a rev limiter...)

I'd start with what Andy suggested, but hopefully you kept track of how much you turned that screw. Possibly just put it back and start with some new plugs and see what happens.

Good Luck!

 

[matt1280]

i took the car to a shop and they told me that it could be the maf sensor. let me know if that sounds correct before i go spending around 200 for the sensor. i really need to know because i have no ride otherwise. when i boost up it sounds okay till the boost get high on the gauge and it studders and shoots out black smoke. i hear a lot of boost coming from the intake, maybe a leak somewhere.

ps- how do i do a boost leak test?

thanks,
matt

 

[andymoraitis]

Info on making a boost leak tester can be found here:

http://www.vfaq.com/mods/ICtester.html

Also, if you pick up a Haynes or Chilton's manual, there are procedures to test the MAF before buying a new one.

Did you check any of the other things on the lists we gave you?

 

[guiliog]

hey guys. I know this is a really old tread but my '98 get is having the same exact problem under full boost at 3,500-4k rpm. It does pop and spit black smoke under boost. Timing issue??? Please help I love my DSM . Mods are a JDM 16g turbo at 12 psi( no boost gauge, was told this buy seller) Apr head studs, forged crank shaft , crank shaft balance delete, injen intake, stage 2 clutch, ngk wires . Any help would be helpful. Thanks

 

[4everboosted]

hey guys. I know this is a really old tread but my '98 get is having the same exact problem under full boost at 3,500-4k rpm. It does pop and spit black smoke under boost. Timing issue??? Please help I love my DSM . Mods are a JDM 16g turbo at 12 psi( no boost gauge, was told this buy seller) Apr head studs, forged crank shaft , crank shaft balance delete, injen intake, stage 2 clutch, ngk wires . Any help would be helpful. Thanks

Do a boost leak test and let me know what you find. I have been tracking down the same problem, I have a major boost leak and some turbo issues. Every thread I read seems to end up a boost leak somewhere. Check it out and see

 

[jaimegonzal101]

I would turn down the boost till you get a boost gauge man. Better safe than sorry. I had fuel cut around 15-16 psi with a 16g but that was because I had stock injectors. I don't think it is the same situation as you though since I never saw black smoke but just throwing that out there.

 

[guiliog]

I've had boost leaks in the past on my previous 3 2g DSM . This doesn't feel the same. Its a fresh rebuilt motor with less than 600 miles on it and everything was looked over . This problem just didn't pop up out of the blue. It started with a real small hickup around this rpm range a few days ago under full boost then turned into this backfiring under acceleration (under full boost) and wont really move. I definitely will look but I believe it is timing related. I believe another guy on here said the same thing, and my old ass father said the same thing as well.

 

[athlete3344]

A BLT doesnt take very much time. Timing is easy to check, either the marks line up or they dont. Why not do both?

 

[guiliog]

A BLT doesnt take very much time. Timing is easy to check, either the marks line up or they dont. Why not do both?

Oh i will bro for sure. To be on the safe side